mirror of https://github.com/python/cpython
603 lines
18 KiB
C
603 lines
18 KiB
C
/* Generator object implementation */
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#include "Python.h"
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#include "frameobject.h"
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#include "structmember.h"
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#include "opcode.h"
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static PyObject *gen_close(PyGenObject *gen, PyObject *args);
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static int
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gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
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{
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Py_VISIT((PyObject *)gen->gi_frame);
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Py_VISIT(gen->gi_code);
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Py_VISIT(gen->gi_name);
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Py_VISIT(gen->gi_qualname);
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return 0;
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}
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void
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_PyGen_Finalize(PyObject *self)
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{
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PyGenObject *gen = (PyGenObject *)self;
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PyObject *res;
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PyObject *error_type, *error_value, *error_traceback;
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if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL)
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/* Generator isn't paused, so no need to close */
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return;
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/* Save the current exception, if any. */
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PyErr_Fetch(&error_type, &error_value, &error_traceback);
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res = gen_close(gen, NULL);
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if (res == NULL)
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PyErr_WriteUnraisable(self);
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else
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Py_DECREF(res);
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/* Restore the saved exception. */
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PyErr_Restore(error_type, error_value, error_traceback);
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}
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static void
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gen_dealloc(PyGenObject *gen)
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{
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PyObject *self = (PyObject *) gen;
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_PyObject_GC_UNTRACK(gen);
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if (gen->gi_weakreflist != NULL)
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PyObject_ClearWeakRefs(self);
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_PyObject_GC_TRACK(self);
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if (PyObject_CallFinalizerFromDealloc(self))
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return; /* resurrected. :( */
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_PyObject_GC_UNTRACK(self);
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Py_CLEAR(gen->gi_frame);
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Py_CLEAR(gen->gi_code);
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Py_CLEAR(gen->gi_name);
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Py_CLEAR(gen->gi_qualname);
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PyObject_GC_Del(gen);
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}
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static PyObject *
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gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
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{
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PyThreadState *tstate = PyThreadState_GET();
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PyFrameObject *f = gen->gi_frame;
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PyObject *result;
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if (gen->gi_running) {
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PyErr_SetString(PyExc_ValueError,
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"generator already executing");
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return NULL;
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}
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if (f == NULL || f->f_stacktop == NULL) {
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/* Only set exception if called from send() */
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if (arg && !exc)
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PyErr_SetNone(PyExc_StopIteration);
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return NULL;
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}
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if (f->f_lasti == -1) {
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if (arg && arg != Py_None) {
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PyErr_SetString(PyExc_TypeError,
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"can't send non-None value to a "
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"just-started generator");
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return NULL;
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}
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} else {
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/* Push arg onto the frame's value stack */
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result = arg ? arg : Py_None;
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Py_INCREF(result);
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*(f->f_stacktop++) = result;
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}
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/* Generators always return to their most recent caller, not
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* necessarily their creator. */
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Py_XINCREF(tstate->frame);
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assert(f->f_back == NULL);
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f->f_back = tstate->frame;
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gen->gi_running = 1;
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result = PyEval_EvalFrameEx(f, exc);
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gen->gi_running = 0;
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/* Don't keep the reference to f_back any longer than necessary. It
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* may keep a chain of frames alive or it could create a reference
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* cycle. */
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assert(f->f_back == tstate->frame);
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Py_CLEAR(f->f_back);
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/* If the generator just returned (as opposed to yielding), signal
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* that the generator is exhausted. */
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if (result && f->f_stacktop == NULL) {
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if (result == Py_None) {
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/* Delay exception instantiation if we can */
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PyErr_SetNone(PyExc_StopIteration);
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} else {
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PyObject *e = PyObject_CallFunctionObjArgs(
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PyExc_StopIteration, result, NULL);
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if (e != NULL) {
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PyErr_SetObject(PyExc_StopIteration, e);
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Py_DECREF(e);
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}
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}
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Py_CLEAR(result);
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}
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if (!result || f->f_stacktop == NULL) {
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/* generator can't be rerun, so release the frame */
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/* first clean reference cycle through stored exception traceback */
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PyObject *t, *v, *tb;
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t = f->f_exc_type;
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v = f->f_exc_value;
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tb = f->f_exc_traceback;
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f->f_exc_type = NULL;
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f->f_exc_value = NULL;
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f->f_exc_traceback = NULL;
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Py_XDECREF(t);
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Py_XDECREF(v);
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Py_XDECREF(tb);
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gen->gi_frame->f_gen = NULL;
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gen->gi_frame = NULL;
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Py_DECREF(f);
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}
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return result;
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}
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PyDoc_STRVAR(send_doc,
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"send(arg) -> send 'arg' into generator,\n\
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return next yielded value or raise StopIteration.");
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PyObject *
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_PyGen_Send(PyGenObject *gen, PyObject *arg)
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{
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return gen_send_ex(gen, arg, 0);
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}
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PyDoc_STRVAR(close_doc,
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"close() -> raise GeneratorExit inside generator.");
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/*
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* This helper function is used by gen_close and gen_throw to
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* close a subiterator being delegated to by yield-from.
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*/
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static int
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gen_close_iter(PyObject *yf)
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{
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PyObject *retval = NULL;
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_Py_IDENTIFIER(close);
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if (PyGen_CheckExact(yf)) {
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retval = gen_close((PyGenObject *)yf, NULL);
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if (retval == NULL)
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return -1;
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} else {
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PyObject *meth = _PyObject_GetAttrId(yf, &PyId_close);
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if (meth == NULL) {
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if (!PyErr_ExceptionMatches(PyExc_AttributeError))
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PyErr_WriteUnraisable(yf);
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PyErr_Clear();
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} else {
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retval = PyObject_CallFunction(meth, "");
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Py_DECREF(meth);
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if (retval == NULL)
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return -1;
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}
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}
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Py_XDECREF(retval);
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return 0;
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}
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static PyObject *
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gen_yf(PyGenObject *gen)
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{
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PyObject *yf = NULL;
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PyFrameObject *f = gen->gi_frame;
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if (f && f->f_stacktop) {
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PyObject *bytecode = f->f_code->co_code;
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unsigned char *code = (unsigned char *)PyBytes_AS_STRING(bytecode);
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if (code[f->f_lasti + 1] != YIELD_FROM)
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return NULL;
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yf = f->f_stacktop[-1];
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Py_INCREF(yf);
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}
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return yf;
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}
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static PyObject *
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gen_close(PyGenObject *gen, PyObject *args)
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{
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PyObject *retval;
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PyObject *yf = gen_yf(gen);
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int err = 0;
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if (yf) {
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gen->gi_running = 1;
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err = gen_close_iter(yf);
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gen->gi_running = 0;
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Py_DECREF(yf);
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}
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if (err == 0)
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PyErr_SetNone(PyExc_GeneratorExit);
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retval = gen_send_ex(gen, Py_None, 1);
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if (retval) {
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Py_DECREF(retval);
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PyErr_SetString(PyExc_RuntimeError,
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"generator ignored GeneratorExit");
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return NULL;
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}
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if (PyErr_ExceptionMatches(PyExc_StopIteration)
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|| PyErr_ExceptionMatches(PyExc_GeneratorExit)) {
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PyErr_Clear(); /* ignore these errors */
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Py_INCREF(Py_None);
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return Py_None;
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}
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return NULL;
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}
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PyDoc_STRVAR(throw_doc,
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"throw(typ[,val[,tb]]) -> raise exception in generator,\n\
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return next yielded value or raise StopIteration.");
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static PyObject *
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gen_throw(PyGenObject *gen, PyObject *args)
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{
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PyObject *typ;
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PyObject *tb = NULL;
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PyObject *val = NULL;
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PyObject *yf = gen_yf(gen);
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_Py_IDENTIFIER(throw);
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if (!PyArg_UnpackTuple(args, "throw", 1, 3, &typ, &val, &tb))
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return NULL;
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if (yf) {
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PyObject *ret;
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int err;
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if (PyErr_GivenExceptionMatches(typ, PyExc_GeneratorExit)) {
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gen->gi_running = 1;
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err = gen_close_iter(yf);
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gen->gi_running = 0;
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Py_DECREF(yf);
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if (err < 0)
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return gen_send_ex(gen, Py_None, 1);
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goto throw_here;
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}
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if (PyGen_CheckExact(yf)) {
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gen->gi_running = 1;
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ret = gen_throw((PyGenObject *)yf, args);
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gen->gi_running = 0;
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} else {
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PyObject *meth = _PyObject_GetAttrId(yf, &PyId_throw);
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if (meth == NULL) {
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if (!PyErr_ExceptionMatches(PyExc_AttributeError)) {
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Py_DECREF(yf);
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return NULL;
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}
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PyErr_Clear();
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Py_DECREF(yf);
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goto throw_here;
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}
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gen->gi_running = 1;
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ret = PyObject_CallObject(meth, args);
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gen->gi_running = 0;
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Py_DECREF(meth);
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}
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Py_DECREF(yf);
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if (!ret) {
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PyObject *val;
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/* Pop subiterator from stack */
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ret = *(--gen->gi_frame->f_stacktop);
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assert(ret == yf);
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Py_DECREF(ret);
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/* Termination repetition of YIELD_FROM */
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gen->gi_frame->f_lasti++;
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if (_PyGen_FetchStopIterationValue(&val) == 0) {
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ret = gen_send_ex(gen, val, 0);
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Py_DECREF(val);
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} else {
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ret = gen_send_ex(gen, Py_None, 1);
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}
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}
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return ret;
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}
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throw_here:
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/* First, check the traceback argument, replacing None with
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NULL. */
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if (tb == Py_None) {
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tb = NULL;
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}
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else if (tb != NULL && !PyTraceBack_Check(tb)) {
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PyErr_SetString(PyExc_TypeError,
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"throw() third argument must be a traceback object");
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return NULL;
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}
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Py_INCREF(typ);
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Py_XINCREF(val);
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Py_XINCREF(tb);
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if (PyExceptionClass_Check(typ))
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PyErr_NormalizeException(&typ, &val, &tb);
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else if (PyExceptionInstance_Check(typ)) {
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/* Raising an instance. The value should be a dummy. */
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if (val && val != Py_None) {
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PyErr_SetString(PyExc_TypeError,
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"instance exception may not have a separate value");
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goto failed_throw;
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}
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else {
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/* Normalize to raise <class>, <instance> */
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Py_XDECREF(val);
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val = typ;
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typ = PyExceptionInstance_Class(typ);
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Py_INCREF(typ);
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if (tb == NULL)
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/* Returns NULL if there's no traceback */
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tb = PyException_GetTraceback(val);
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}
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}
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else {
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/* Not something you can raise. throw() fails. */
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PyErr_Format(PyExc_TypeError,
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"exceptions must be classes or instances "
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"deriving from BaseException, not %s",
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Py_TYPE(typ)->tp_name);
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goto failed_throw;
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}
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PyErr_Restore(typ, val, tb);
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return gen_send_ex(gen, Py_None, 1);
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failed_throw:
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/* Didn't use our arguments, so restore their original refcounts */
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Py_DECREF(typ);
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Py_XDECREF(val);
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Py_XDECREF(tb);
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return NULL;
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}
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static PyObject *
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gen_iternext(PyGenObject *gen)
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{
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return gen_send_ex(gen, NULL, 0);
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}
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/*
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* If StopIteration exception is set, fetches its 'value'
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* attribute if any, otherwise sets pvalue to None.
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*
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* Returns 0 if no exception or StopIteration is set.
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* If any other exception is set, returns -1 and leaves
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* pvalue unchanged.
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*/
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int
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_PyGen_FetchStopIterationValue(PyObject **pvalue) {
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PyObject *et, *ev, *tb;
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PyObject *value = NULL;
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if (PyErr_ExceptionMatches(PyExc_StopIteration)) {
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PyErr_Fetch(&et, &ev, &tb);
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Py_XDECREF(et);
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Py_XDECREF(tb);
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if (ev) {
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value = ((PyStopIterationObject *)ev)->value;
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Py_INCREF(value);
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Py_DECREF(ev);
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}
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} else if (PyErr_Occurred()) {
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return -1;
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}
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if (value == NULL) {
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value = Py_None;
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Py_INCREF(value);
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}
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*pvalue = value;
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return 0;
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}
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static PyObject *
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gen_repr(PyGenObject *gen)
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{
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return PyUnicode_FromFormat("<generator object %S at %p>",
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gen->gi_qualname, gen);
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}
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static PyObject *
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gen_get_name(PyGenObject *op)
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{
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Py_INCREF(op->gi_name);
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return op->gi_name;
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}
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static int
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gen_set_name(PyGenObject *op, PyObject *value)
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{
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PyObject *tmp;
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/* Not legal to del gen.gi_name or to set it to anything
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* other than a string object. */
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if (value == NULL || !PyUnicode_Check(value)) {
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PyErr_SetString(PyExc_TypeError,
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"__name__ must be set to a string object");
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return -1;
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}
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tmp = op->gi_name;
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Py_INCREF(value);
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op->gi_name = value;
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Py_DECREF(tmp);
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return 0;
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}
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static PyObject *
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gen_get_qualname(PyGenObject *op)
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{
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Py_INCREF(op->gi_qualname);
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return op->gi_qualname;
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}
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static int
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gen_set_qualname(PyGenObject *op, PyObject *value)
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{
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PyObject *tmp;
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/* Not legal to del gen.__qualname__ or to set it to anything
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* other than a string object. */
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if (value == NULL || !PyUnicode_Check(value)) {
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PyErr_SetString(PyExc_TypeError,
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"__qualname__ must be set to a string object");
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return -1;
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}
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tmp = op->gi_qualname;
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Py_INCREF(value);
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op->gi_qualname = value;
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Py_DECREF(tmp);
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return 0;
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}
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static PyGetSetDef gen_getsetlist[] = {
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{"__name__", (getter)gen_get_name, (setter)gen_set_name,
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PyDoc_STR("name of the generator")},
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{"__qualname__", (getter)gen_get_qualname, (setter)gen_set_qualname,
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PyDoc_STR("qualified name of the generator")},
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{NULL} /* Sentinel */
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};
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static PyMemberDef gen_memberlist[] = {
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{"gi_frame", T_OBJECT, offsetof(PyGenObject, gi_frame), READONLY},
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{"gi_running", T_BOOL, offsetof(PyGenObject, gi_running), READONLY},
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{"gi_code", T_OBJECT, offsetof(PyGenObject, gi_code), READONLY},
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{NULL} /* Sentinel */
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};
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static PyMethodDef gen_methods[] = {
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{"send",(PyCFunction)_PyGen_Send, METH_O, send_doc},
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{"throw",(PyCFunction)gen_throw, METH_VARARGS, throw_doc},
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{"close",(PyCFunction)gen_close, METH_NOARGS, close_doc},
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{NULL, NULL} /* Sentinel */
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};
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PyTypeObject PyGen_Type = {
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PyVarObject_HEAD_INIT(&PyType_Type, 0)
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"generator", /* tp_name */
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sizeof(PyGenObject), /* tp_basicsize */
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0, /* tp_itemsize */
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/* methods */
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(destructor)gen_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_reserved */
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(reprfunc)gen_repr, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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0, /* tp_call */
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0, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
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Py_TPFLAGS_HAVE_FINALIZE, /* tp_flags */
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0, /* tp_doc */
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(traverseproc)gen_traverse, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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offsetof(PyGenObject, gi_weakreflist), /* tp_weaklistoffset */
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PyObject_SelfIter, /* tp_iter */
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(iternextfunc)gen_iternext, /* tp_iternext */
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gen_methods, /* tp_methods */
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gen_memberlist, /* tp_members */
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gen_getsetlist, /* tp_getset */
|
|
0, /* tp_base */
|
|
0, /* tp_dict */
|
|
|
|
0, /* tp_descr_get */
|
|
0, /* tp_descr_set */
|
|
0, /* tp_dictoffset */
|
|
0, /* tp_init */
|
|
0, /* tp_alloc */
|
|
0, /* tp_new */
|
|
0, /* tp_free */
|
|
0, /* tp_is_gc */
|
|
0, /* tp_bases */
|
|
0, /* tp_mro */
|
|
0, /* tp_cache */
|
|
0, /* tp_subclasses */
|
|
0, /* tp_weaklist */
|
|
0, /* tp_del */
|
|
0, /* tp_version_tag */
|
|
_PyGen_Finalize, /* tp_finalize */
|
|
};
|
|
|
|
PyObject *
|
|
PyGen_NewWithQualName(PyFrameObject *f, PyObject *name, PyObject *qualname)
|
|
{
|
|
PyGenObject *gen = PyObject_GC_New(PyGenObject, &PyGen_Type);
|
|
if (gen == NULL) {
|
|
Py_DECREF(f);
|
|
return NULL;
|
|
}
|
|
gen->gi_frame = f;
|
|
f->f_gen = (PyObject *) gen;
|
|
Py_INCREF(f->f_code);
|
|
gen->gi_code = (PyObject *)(f->f_code);
|
|
gen->gi_running = 0;
|
|
gen->gi_weakreflist = NULL;
|
|
if (name != NULL)
|
|
gen->gi_name = name;
|
|
else
|
|
gen->gi_name = ((PyCodeObject *)gen->gi_code)->co_name;
|
|
Py_INCREF(gen->gi_name);
|
|
if (qualname != NULL)
|
|
gen->gi_qualname = qualname;
|
|
else
|
|
gen->gi_qualname = gen->gi_name;
|
|
Py_INCREF(gen->gi_qualname);
|
|
_PyObject_GC_TRACK(gen);
|
|
return (PyObject *)gen;
|
|
}
|
|
|
|
PyObject *
|
|
PyGen_New(PyFrameObject *f)
|
|
{
|
|
return PyGen_NewWithQualName(f, NULL, NULL);
|
|
}
|
|
|
|
int
|
|
PyGen_NeedsFinalizing(PyGenObject *gen)
|
|
{
|
|
int i;
|
|
PyFrameObject *f = gen->gi_frame;
|
|
|
|
if (f == NULL || f->f_stacktop == NULL)
|
|
return 0; /* no frame or empty blockstack == no finalization */
|
|
|
|
/* Any block type besides a loop requires cleanup. */
|
|
for (i = 0; i < f->f_iblock; i++)
|
|
if (f->f_blockstack[i].b_type != SETUP_LOOP)
|
|
return 1;
|
|
|
|
/* No blocks except loops, it's safe to skip finalization. */
|
|
return 0;
|
|
}
|